In pressurized fluid systems or vessel components, pipe flanges are used to connect and seal adjoining pipe sections. In many systems containing pressurized fluids, additional insert devices are installed by means of an internal placement within the bolting pattern of exterior companion pipe flanges. These insert devices have a particular function depending upon the specific application of the underlying system. Representative examples of insert devices for placement within pressurized fluid systems include, but are not limited to, rupture disks, steam traps, check valves, and orifice plates. For example, a rupture disk will vent fluid from the system when the pressure in the system reaches an unsafe level. A number of emergency conditions, including fire and system failure, can create dangerous pressure levels, which require immediate relief to preserve the safety of the system.
Generally, a pressure relief assembly includes a rupture disk that is associated upon installation with a unitary, single member holder or sealed between a pair of such support members, or safety heads. The pressure relief assembly is then sealingly disposed between a pair of conventional pipe flanges in a conduit of the pressurized system. One side of the conduit conducts pressurized fluid to one side of the pressure relief assembly, and the other side of the conduit pipe provides an outlet to a safety reservoir or to the environment. The support members include a central opening that exposes a portion of the rupture disk to the pressurized fluid in the system. The exposed portion of the rupture disk will rupture when the pressure of the fluid reaches a predetermined differential pressure between the inlet and outlet sides. The ruptured disk creates a vent path that allows fluid to escape through the outlet to reduce the pressure in the system.
In an emergency situation, where the system pressure becomes unsafe, it is important to reduce the pressure as quickly as possible. The American Society of Mechanical Engineers (ASME) codes establish minimum performance requirements for fluid flow through pressure relief systems. The size and shape of the opening created when the disk bursts is a limiting factor on the rate at which fluid can escape the system. A burst disk having a large, unobstructed opening will perform better than a burst disk having a small, obstructed opening because the velocity head loss (i.e. pressure drop) over the large, unobstructed opening will be lower than the velocity head loss over a smaller or obstructed opening. The lower velocity head loss translates to a lower flow resistance (Kr) and, thus, a greater flow rate through the disk device.
Another factor which affects flow resistance of the system is the positioning of the pressure relief assembly with respect to the companion bolted flanges. If the pressure relief assembly is precisely centered within the bolted flange members, the path created when the disk bursts will more consistently lead to a larger and less obstructed opening. Conversely, where an insert device is positioned in an off-center manner, the velocity head loss over this smaller opening will create a larger pressure drop that may create an undesirable situation.
As mentioned above, many insert devices are installed into pressure systems by means of conventional pipe flanges. Conventional pipe flanges are constructed according to standardized guidelines. In the United States, pipe flanges are produced according to standards provided by the American National Standards Institute (ANSI) and the American Society of Mechanical Engineers. ANSI and ASME standards require that for a particular nominal size and pressure rating, the particular flange has standard specifications regarding such factors as, the number of bolts, the size of bolt holes, bolt spacing, and flange overall dimensions. Conversely, in other countries different standards are used. In Germany, for example, flanges are constructed according to the German Industrial Norm (DIN). Japan uses the Japanese Industrial Standard (JIS). Great Britain uses the BS Standard. The European Union has introduced EN standards for pipe flanges.
These design standards differ in that each standard requires a distinct bolt pattern and normally circular flange configuration corresponding to a particular pressure rating and nominal size. Accordingly, due to the difference in international flange design standards, a pressure relief assembly will require individualized positioning within a particular system depending upon the particular flange standard used. These differences require that assemblies, such as safety heads or the insert device itself in instances where the holder is integral to the insert device, be individually manufactured to fit the specific flange standard for which they are to be ultimately installed. In addition, traditional gaskets used for creating fluid tight seals in pressurized systems must also be specifically fit for particular flange sizes and international standards.
In light of the foregoing, there is a need for a flange adapter that allows for the positioning and centering of an insert device or gasket within companion bolted flanges of differing design standards and pressure ratings. It would be desirable from a cost-effectiveness standpoint to have a flange adapter that could be manufactured from inexpensive materials, such as bar stock or sheet material.
Insert devices and gaskets placed within a pressurized fluid system often require strict maintenance and inspection for proper performance and replacement. Devices inserted within pressurized fluid systems often are cumbersome to remove from within companion bolted flange members. This process requires the removal of multiple bolts to reach the insert device or gasket followed by re-installation and precise torqueing between the flange members. Accordingly, there is also a need for an adapter device which facilitates removal and reassembly of insert devices and gaskets from within bolted flange members within a pressurized fluid system.
Different aspects of the present invention provide a solution to each of these identified problems.